The present invention generally relates to a light emitting semiconductor device with a flip-chip package structure, especially to a light emitting semiconductor device with a surface-mounted and flip-chip package structure.
Traditionally, the package structures of light emitting semiconductor devices include xe2x80x9clead-typesxe2x80x9d and xe2x80x9cchip-typesxe2x80x9d. A lead-type package structure of a light emitting semiconductor device is shown in FIG. 1. The light emitting diode 100 includes a light emitting component 102, a mount lead 105 and an inner lead 106. The mount lead 105 includes a cup 105a and a lead 105b. The light emitting component 102 is installed on the recess of the cup 105a, which is filled with an epoxy coating resin 101. In this way, the light emitting component 102 can be sealed in the coating resin 101. Then, the N-type electrode and the P-type electrode (not shown) of the light emitting component 102 are connected to the mount lead 105 and the inner lead 106 via the conductive wires 103, respectively. Finally, the light emitting component 102 and part of the mount lead 105 and the inner lead 106 are encapsulated in the molding material 104.
FIG. 2 shows the sectional view of a structure of a conventional LED.
The LED 200 is a GaN-based light emitting diode. As shown in the figure, the LED 200 includes a sapphire substrate 201 and a multi-layer structure consisted of an N-type GaN semiconductor layer 202 and a P-type GaN semiconductor layer 203. The N-type GaN semiconductor layer is formed on the surface of the sapphire substrate and the P-type GaN semiconductor layer is formed on the surface of the N-type GaN semiconductor layer. The P-type GaN semiconductor layer 203 is etched to form a exposed area 206 on the surface of the N-type GaN semiconductor layer 202, and an N-type electrode 205 is set up thereon. Meanwhile, a transparent P-type electrode 204 is formed on the surface of the P-type GaN semiconductor layer 203. A P-type electrode area (not shown) is defined on the transparent electrode 204 to expose part of the surface of the P-type GaN semiconductor layer 203. A P-type electrode 207 is then formed on the exposed area of the P-type GaN semiconductor layer 203 and electrically connected to the transparent electrode 204. Then, a traditional lead-type LED is formed.
Similarly, a chip-type LED package structure is shown as FIG. 3. In FIG. 3, the light emitting semiconductor device 300 includes an LED dice 303 fixed on a lead frame 302 with silver paste. The lead frame 302 is formed on the insulating substrate 301. Then, the steps of wire-bonding, encapsulating and dicing are processed in sequence. As to the wire-bonding step, the connecting points 304 of the LED dice 303 are connected to the lead frame 302 by gold leads 305. For the encapsulating step, the lead frame 302 is preheated on a framework and transferred into a laminator with the framework. In the laminator, an epoxy resin is filled into the framework and a hardening step is processed. After the encapsulating step, the LED dice 303 is encapsulated in a plastic cube 306 filled with an epoxy resin.
According to the package structure of the traditional light emitting semiconductor devices described above, all of the packaging steps, such as die bonding, wire bonding and encapsulating, are required in both the lead type structure and the chip-type structure. These manufacturing steps make it difficult to minimize the size of the device, and the manufacturing cost of the device cannot be reduced. Hence, it is required to simplify the packaging processes of the light emitting semiconductor devices.
Therefore, one object of the present invention is to provide an improved light emitting semiconductor device with simplified package structure.
Another object of the present invention is to provide an improved light emitting semiconductor device with a lower manufacturing cost.
Moreover, another object of the present invention is to provide an improved light emitting semiconductor device with higher light-emitting efficiency.
The light emitting semiconductor device of the present invention comprises: an insulating substrate; an LED, which includes a substrate, a first-type semiconductor layer formed on the substrate surface, a first electrode formed on part of the first-type semiconductor layer surface, a second-type semiconductor layer formed on the surface of the first-type semiconductor layer but does not cover the first electrode, and a second electrode formed on the surface of the second-type semiconductor layer; two bumps, formed on the insulating substrate; and two electrode layers, formed on the two sides of the insulating substrate and extend upwardly and downwardly to the upper and lower surface of the insulating substrate. The first and second electrodes of the LED are connected to the insulating substrate via the two bumps respectively. Meanwhile, the upper parts of the two electrode layers are connected with the first and second electrode of the LED via the two bumps.
According to the package structure described above, the light emitting semiconductor device of the present invention has both of the advantages of the flip-chip package structure and the surface-mounting process.
Meanwhile, the insulating substrate of the light emitting semiconductor device of the present invention has a thermal-expansion coefficient similar to an LED and a thermal-conductivity similar to a metal material. Hence, the device of the present invention possess a lower stress and better reliability, and can be operated with high power.
Further, the light emitting semiconductor device of the present invention is backside light-emitted type. Therefore, the device can reduce the light shelter effect caused by the electrodes and have higher light-emitted efficiency than the conventional light emitting semiconductor devices. Moreover, the device of the present invention is packaged with Surface-Mounting technology. This method simplifies the manufacturing process of the device and minimizes the size thereof.
Further, the packaging material of the present invention is cheaper than the traditional LED packaging materials. Hence, the manufacturing cost of the device is reduced.